RadioShack just confirmed to 9to5Mac that every location nationwide has discounted the 16GB iPhone 5 to $149.99 and 16GB iPhone 4S to $49.99 as part of an in-store only sale that price matches Best Buy’s current $50-off offering.

RadioShack is applying the same discount to the iPhone’s remaining capacities with a new two-year agreement. The holiday price cut means folks can grab the 16GB version for $149.99, the 32GB version for $249.99, and the 64GB for $349.99.

In addition, RadioShack offers shoppers $10 back on every $50 they spend through the holiday season via an email coupon toward a future purchase. More details available at RadioShack.com. But that’s not all…

We contacted Walmart to see if it would match both Best Buy and RadioShack. While we are still waiting for an official statement from corporate, many select Walmart Wireless centers in New York, New Jersey, and Vermont, said they would honor the sale. One store in New Jersey, however, claimed Wireless centers do not price match. Walmart does not mention this stipulation on its Match Guarantee page, though.

We recently reported that Target offers AT&T’s iPhone 5 with a $20 discount in-stores only until Dec. 15. 9to5Mac reached out to many Target locations to see if they also planned to lower the 16GB iPhone 5 price tag to $149. While at least one location verified it would price match Best Buy, RadioShack, and Walmart, we further contacted Target headquarters to find out more.

Apple stores often match prices of competitors as well, and at least one store we called said it would honor Best Buy’s price. We will update when more information is available.

UPDATE: Walmart-owned Sam’s Club just slashed $50 off the iPhone 5 and iPhone 4S with a new two-year agreement until Dec. 30. Offer is valid in stores only with a limit of five per customer. More details are available at Sam’s Club.